The tuba (Latin, "trumpet"; ; ) is a large brass instrument in the bass-to-contrabass range with a wide conical bore. It usually has four or five valves, although some models have three and some have
1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x6fb49e9fbd1ce5ff0a2fe973184a376f1c14fd3bd01ad849f5d3c59bc187a0e5. Chain 2 (Bitcoin): anchored in block 953949 (2026-06-16T13:28:01Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/1d1f0d94-2550-416a-b71f-0480a9072a49.json and https://artists.proofprofile.net/proofs/artist/1d1f0d94-2550-416a-b71f-0480a9072a49.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).